SANFORD — The police chief who for weeks has faced a firestorm of criticism over the shooting death of Trayvon Martin said Thursday that he is stepping down temporarily.

Bill Lee Jr., who became Sanford's police chief in April after 27 years as a Seminole County deputy, said he is a "distraction" in the death of 17-year-old Trayvon.

"I do this in the hopes of restoring some semblance of calm to a city which has been in turmoil for several weeks," said Lee, 52, in a brief news conference.

His announcement did little to appease protesters furious that he did not arrest the shooter, crime-watch volunteer George Zimmerman, who claimed self-defense in the Feb. 26 shooting.

A short time after the chief's announcement, Trayvon's father, Tracy Martin, told a cheering crowd in Sanford that Lee's move "is nothing. We want an arrest. We want a conviction, and we want him [Zimmerman] sentenced for the murder of our son."

When Lee became chief less than a year ago, beating out 175 other applicants, he took over an agency with major problems: a town with hard-core urban crime and a hostile black community. Still, Lee said it was his dream job: being chief of police in his hometown.

Lee grew up in a house on Sanford's Hester Street, the son of a city firefighter. He started school in the mid-1960s, when local public schools were still segregated, and graduated from Seminole High School in 1977.

He went through the police academy at what is now Seminole State College and graduated from the University of Central Florida in 1981 with a degree in criminal justice. He would later get a master's degree in public administration, again at UCF, according to his résumé. He graduated from the FBI academy in 2001.

In 1998, Seminole County Sheriff Don Eslinger gave Lee his agency's highest award, its medal of valor for stepping into the open and braving several rounds of gunfire to check on Deputy Eugene Gregory, who lay dead, the victim of a gunman who was hiding behind heavy machinery and holding off a SWAT team by firing thousands of rounds of ammunition.

Now, Lee, who is married with three sons, is the focus of increasing anger at the way Trayvon's death was handled.

He has insisted his agency did a fair and thorough investigation. He could not lawfully arrest Zimmerman, who shot and killed Trayvon as the teen walked through his gated community, because evidence backs up Zimmerman's claim of self-defense, he said.

He would not discuss it, but Pat Whitaker, chief of operations at the State Attorney's Office in Sanford, said Thursday night that the case's key evidence has not yet been made public.

"There's just so much more to it that has not been disclosed," he said. "What you have is not the crucial evidence."

Black leaders, including NAACP President Ben Jealous, said the chief has to go.

Jealous called Lee's move Thursday a good first step.

"When you think back to the start of this week, we didn't know how the state's attorney would respond, we didn't know if DOJ [Department of Justice} would investigate, we didn't know how the city would handle this chief," he said. "And here we are, just a few days later, and we see that the state's attorney has set a date certain, we see that DOJ is investigating and that this chief has now stepped aside because the city voted that they no longer have faith in his leadership."

Turner Clayton, president of the Seminole County branch of the NAACP, called for the "full termination of the police chief who mishandled this case from the beginning."

Lee's decision to step down temporarily came a day after the Sanford City Commission handed down a 3-2 no-confidence vote. The commission does not have the authority to fire the chief because he reports to the city manager.

"I never thought he was a racist," said Velma Williams, the one black member of Sanford's City Commission. "I think it's a matter of lack of experience."

Lee has said little about the case, standard operating procedure for a pending investigation, and would not discuss his decision.

Lee, who makes $102,000 a year and will continue to draw a paycheck, will not be able to return without the city manager's authorization, said police Sgt. David Morgenstern.

Protesters say they will not be satisfied until Zimmerman, 28, is arrested. They have staged rallies in Sanford, New York, Miami and Tallahassee. On Thursday night, several thousand gathered for a rally led by activist the Rev. Al Sharpton in Fort Mellon Park.

Last week, police officially handed over the case to the State Attorney's Office, leaving prosecutors to decide whether to charge Zimmerman with manslaughter or some other crime.On Thursday night, Gov. Rick Scott appointed a special prosecutor, Angela Corey, the state attorney in Jacksonville.

It was not clear Thursday night whether she would present the case to a Seminole County grand jury, something Sanford prosecutors had scheduled for April 10.